A posttraumatic radiography in an 11-year-old boy with known postaxial polydactyly in the context of an Ellis-van Creveld syndrome, revealed—besides the radial fracture—at the ulnar side of the distal carpal row a fifth bone and at its radial side an abnormal large carpal bone.
A fifth distal carpal bone (FDCB) was present at the ulnar side, articulating with the V-VI-synmetacarpal.
The adjacent large bone resembled at its radial side a capitate bone with a rounded head proximally articulating with the lunate bone and the long flexor tendons were running radially of the hamulus at its ulnar-palmar side, hallmarks of a ham-shaped hamato-capitate fusion bone (HCFB).
The more centrally located bone articulated with the 3rd metacarpal distally, extended to the scapholunate joint and had a rounded head proximally communicating with a smaller facet at the radial side of the lunate bone. The radioscaphocapitate ligament and part of the thumb adductor muscle were attached to it, a deep groove at the radial side formed its neck and part of the thumb adductor muscle was running past it and the base of the 3rd metacarpal. This was considered as a smaller capitate bone (C).
The autosomal recessive Ellis-van Creveld syndrome (EvC) is reported in 1 in 1,500,000 births with an equal sex ratio. About 300 cases have been reported.
Bilateral postaxial polydactyly is a constant finding in the hands and is present in about 10% of the feet [1, 2]. There are two types (A: well-formed digit and B: rudimentary skin tag). Short limbs (mesomelic) are responsable for a disproportionate dwarfism. The short ribs cause a narrow thoracic cage with vital capacity reduction. Congenital heart defects occur in about 60%. A third of EvC die of cardiac or respiratory distress in infancy. The surviving patients have a normal life expectancy [1], psychomotor and cognitive development [3].
Previously, polydactylies were considered duplication defects. 1/600 newborns present with an upper limb abnormality [4]. They have a high perinatal mortality rate [5]. Most congenital defects of the hand have a monogenic basis, especially when they are bilateral [2]. EvC is caused by loss-of-function mutations in the genes EVC or EVC2.
Plain radiography and MRI of the hand show a constant bilateral hexadactyly [1]. Five subtypes of postaxial polydactyly are identified in type A [6]. All metacarpals are shortened and broad. The extra digit has only two phalanges. The proximal phalanx of the 6th digit is hypertrophic. The other proximal and middle phalanges are dumbbell-shaped with a coned epiphyseal ossification centre. The middle and distal phalanges are shorter (acromesomelia). The terminal phalanges are hypoplastic. Fusion of carpal bones is frequent, mostly of the hamate and capitate bone. The ham-shaped HCFB [3, 7] is present in about 25% [8]. All of the previous abnormalities were present in our patient. Accessory carpal bones may be seen, mostly at the ulnar side of the hamate, also known as the Fifth Distal Carpal Bone (FDCB) [7, 8]. When this FDCB, as in our case is not fused with the hamate bone, it articulates with the triquetral bone proximally, the bases of the 5th and/or 6th metacarpals distally and the hamate bone laterally. The abnormalities of the carpal bones tend to be symmetrical [8]. A FDCB fused with HCFB may be unique for EvC [8].
MRI may moreover help to better assess the bony and associated soft tissue abnormalities. The presence and the path of the tendons and ligaments may be clearly demonstrated. Oedema of carpal bones may be present in case of malfunctioning of an aberrant bony configuration.
A rare case of polycarpyly in a patient with Ellis-van Creveld syndrome.
According to the provided X-ray and MRI images, the main observations are as follows:
1. A fracture line is visible in the distal radius of the forearm, indicating a radial fracture.
2. On the ulnar side of the hand, there is a distinct postaxial polydactyly (a sixth finger). This extra finger presents a complete phalangeal structure (Type A type, including at least the proximal and distal phalanges) or at least two phalanges.
3. Abnormal fusion and segmentation are seen among the small bones of the wrist: there is a fusion between the hamate (Hamate) and the capitate (Capitate). Additionally, an extra small bone (the fifth distal carpal bone, FDCB) is observed on the ulnar side, articulating with the triquetrum, the fifth/sixth metacarpal bones, and the hamate.
4. Most of the metacarpal and phalangeal bones appear relatively short and thick, with conical epiphyses in some areas. The proximal and middle phalanges show a “dumbbell-like” shape, and the terminal phalanges are relatively small in development.
5. MRI indicates abnormal morphology and signal changes in multiple wrist bones, with local soft tissue structures demonstrating unusual positioning or traction, suggesting slight variations or tension in adjacent ligaments and tendons.
Based on the aforementioned imaging findings and the known characteristic deformities of the patient, the potential diagnoses include:
1. Ellis-van Creveld Syndrome: Typical manifestations include disproportionate dwarfism (especially shortening of the limbs), postaxial polydactyly, multiple cartilaginous and phalangeal developmental abnormalities, and frequently fusion of certain phalanges or carpal bones. Imaging often reveals fusion of the hamate and capitate and the presence of extra carpal bones.
2. Other syndromes involving complex bone developmental anomalies leading to polydactyly (e.g., certain types of chondrodysplasia or other genetic syndromes): However, the pattern of carpal fusion or extra carpal bones is usually less characteristic than in Ellis-van Creveld Syndrome. These syndromes also often lack some of the comprehensive clinical features noted in this patient (such as a distinct limb-shortening pattern, possible cardiac anomalies, and changes in nails and hair).
Combining the clinical history (including known postaxial polydactyly, short-limb presentation, and characteristic wrist bone changes) with the imaging findings of the carpal and metacarpal-phalangeal bones, the most likely diagnosis is: Ellis-van Creveld Syndrome, with concurrent trauma indicating a distal radial fracture.
If necessary, genetic testing of the EVC or EVC2 genes can provide further confirmation, and other systems (such as the heart) should be assessed to rule out additional complications.
1. Management of the Radial Fracture:
• Depending on the nature of the fracture and the patient’s skeletal maturity, options include conservative or surgical treatment. If alignment is acceptable, casting or splinting may suffice. If there is significant displacement, internal fixation (e.g., plates, screws) or percutaneous Kirschner wire fixation may be required.
• Schedule regular follow-up imaging to monitor healing of the fracture and function of the hand and wrist.
2. Management of Polydactyly:
• If the sixth finger is non-functional or interferes with daily activities, surgical removal or reconstruction can be considered at an appropriate time.
• In Ellis-van Creveld Syndrome, a comprehensive treatment plan should also involve evaluating other skeletal anomalies and cardiopulmonary function.
3. Overall Rehabilitation and Exercise Prescription:
Adopting the FITT-VP principles (Frequency, Intensity, Time, Type, Volume/Progression) for progressive rehabilitation:
• Frequency: At least 3–5 times per week, ensuring regular sessions.
• Intensity: Begin with low-intensity exercises (for instance, non-weight-bearing exercises using supportive devices), increasing resistance or load progressively as the fracture heals and wrist stability improves.
• Time: Start with 5–10 minutes of gentle activity per session in the early phase, potentially several times daily. Gradually extend to 15–20 minutes per session to enhance joint mobility and muscle strength in later phases.
• Type: Focus on active and passive wrist-range-of-motion exercises and hand grip and pinch exercises. Activities such as swimming or light hydrotherapy can help reduce stress on the fracture site.
• Progression: As the fracture heals and pain subsides, increase both the duration and intensity of exercise. Incorporate appropriate resistance training (e.g., elastic bands, light dumbbells). In cases of cardiac abnormalities or limited cardiopulmonary function, consult a physician to adjust exercise modalities and intensity.
In daily life, warm compresses, ultrasound therapy, and joint mobilization may help alleviate soft tissue tension and improve circulation. It is important to monitor the child’s pain and fatigue levels; if any issues arise, consult the physician promptly.
This report provides a reference-based analysis derived from the available imaging and clinical history and does not replace an in-person consultation or professional medical advice. A personalized treatment and rehabilitation plan should be developed and adjusted by the relevant clinical specialists and rehabilitation therapists based on the patient’s individual needs.
A rare case of polycarpyly in a patient with Ellis-van Creveld syndrome.
